M&S says

For unbeatable confidence that you can count on, opt for these comfortable and supportive high-waist slimming shorts. The innovative Thigh Sculpt™ technology delivers firm control to enhance your hourglass look, working to flatten your tummy, smooth your back and lift your bottom for a flattering silhouette. Designed with minimal seams and a plush waistband, these control briefs eliminate any unwanted VPL for no-pinch compression at the thighs.